The legal opinion will go before the Parliament’s bureau – made up of the president, 14 vice-presidents and quaestors – for a decision later this year.

The case arises out of a complaint made by a journalist in 2005 after he was denied access to information about MEPs’ expenses. At the time Parliament said that revealing details of MEPs’ expenses would also disclose personal information about their assistants, whose right to privacy would be infringed. The Parliament also argued that the current system of checks – whereby expenses are scrutinised by the committee on budgetary control and the European Court of Auditors – was sufficient scrutiny.

But in his draft recommendation, published in September, Nikiforos Diamandouros, the European ombudsman, stressed “the great importance of public access to documents with respect to transparency, accountability and democracy in the EU”.

“Access to documents held by public authorities allows citizens to gain an insight into decision-making processes and to scrutinise the administrative functioning of these authorities,” he added.

Once the Parliament’s bureau has made its response to the draft recommendation, the ombudsman will deliver a final recommendation. The Parliament is not obliged to follow the recommendation and can reject it outright.

MEPs’ expenses include a €279 daily allowance to cover meals and hotels, €15,496 per month to hire an assistant, €3,946 per month to run an office in the home constituency and travel expenses.